The present invention relates to a movable supporting construction for placing on a floor. Such a supporting construction is used, for example, as a sea floor reaction mass when conducting a geotechnical survey from aboard a ship. This supporting construction is also referred to as Seabed Frame (SBF) and serves initially as reaction mass to the force needed to push a probe or sample tube into the ground. In addition, the supporting construction has several other functions such as drill-pipe guide, support for measuring, operating and control equipment for the geotechnical survey. The equipment of the supporting construction depends on the survey to be performed. Since the seabed is in general not flat or horizontal, it is important that the supporting construction be operable on a slope. If this is not possible, or only to a lesser extent, the applicability of the supporting construction becomes limited, which is undesirable.
Supporting constructions for operating on a slope exist. These constructions are usually embodied with a fixed hinge point (cardan-like) between two components, of which one has to adapt to the angle of the slope; they may also be provided with an extra device that is actively controlled by means of, for example, hydraulic cylinders. This is often realized after landing, with the aid of measurements. During positioning, also referred to as landing, these constructions are subject to internal frictions resulting from the parts being permanently coupled (cardan or hinge) so that they are either prevented from assuming the correct angle or they require active control. After landing, the components are often not fixed so as to avoid rotation in relation to one another, with the result that relatively minor external forces can cause the support construction to become unstable.
The inability to adequately compensate for the slope may have the following consequences:                difficulties with guiding the drill pipe;        difficulties with inserting the drill-pipe into the construction due to the drill-pipe and the top portion of the construction to be entered being oriented at different angles;        problems with the other means that are pushed or introduced into the ground from or out of the supporting construction, which due to a small movement or due to a large angle difference, are no longer able to fulfill their function, or become damaged.        